It flourished because it was based on the original religion of the world. A monotheistic deity that based it’s stance on godhood by advocating love, peace and friendship which are aspects that man outwardly desire, even if inwardly we act for war, violence and hate.
Heck, even the Muslims worship the same God the Christians do. It’s just a different prophet they cling too.
Jews, Muslims and Christians worship God.
Pagans worship everything, including themselves. (Depends on your flavor of paganism.)
Polytheists worship multiple gods
Buddists/Scientologists worship themselves
Most scientists worship themselves
Athiests/Agnostics don’t worship anything, but they may or may not conceed that a God exists.